Generally, a plurality of materials is formed on a wafer in a thin film shape and the patterned to form a semiconductor device. That is, a deposition process, an etching process, a cleaning process, a drying process, etc. are required to form a semiconductor device.
In order to perform the above process, a wafer transferring apparatus is used for transferring wafers. In this case, a load port is widely used to provide the wafer transferring apparatus such as EFEM with wafers carried by a wafer carrier.
On the other hand, when foreign substance such as dust exists in the wafer carrier, the foreign substance may induce failure of the wafer. Therefore, the foreign substance is removed by gas purging. An initial model of a load port does not have the gas purging function, but a new model of a load port has a nitrogen (N2) purging function purging foreign substance by using nitrogen gas to solve above problem.
However, it is too expensive to substitute all of the conventional load port without a gas purging function with the new load port with the gas purging function.
Furthermore, there are so many kind of wafer carrier. Therefore, when the wafer carrier is changed, a new load port that is proper to the new wafer carrier is required.